Tom Swift Jr. and his associates at Swift Enterprises wait breathlessly for what may well be the most important scientific event in history--the arrival of the visitor from Planet X--a visitor in the form of energy. But there are factions at work determined to snatch the energy, which Tom has named Exman, from the young scientist-inventor's grasp. First, a series of unexplainable, devastating earthquakes threaten to destroy a good portion of the earth, and Tom suspects the Brungarian rebels who obviously would like to capture Exman and use the space visitor to further their own evil purposes.